Discovery counts down toward launch

NASA is counting down to the planned launch Thursday of shuttle Discovery and six astronauts on the orbiter's final flight into space.Grounded for four months by dangerous external tank defects, Discovery and its crew are slated to blast off from Kennedy Space Center at 4:50 p.m. Thursday.The orbiter's 39th flight will cap a career that has included missions to the International Space Station, the Hubble Space Telescope, Russia's space station Mir and the first flights after the 1986 Challenger disaster and the 2003 Columbia accident.John Glenn flew aboard Discovery on his 1998 return to space at age 77."She's taken us on many amazing journeys throughout the years, and we don't expect this flight to be any different than those," NASA Test Director Jeff Spaulding said Monday."She still has a few more miles to go before shesleeps, though," Spaulding said.A three-day launch countdown picked up Monday as NASA geared up for one of only three shuttle missions remaining before fleet retirement.Mission commander Steve Lindsey and his crew aim to deliver a modified Italian cargo carrier to the International Space Station, where it will serve as a badly needed permanent storage unit.The crew arrived at KSC Sunday and includes pilot Eric Boe and four mission specialists: Michael Barratt, Stephen Bowen, Al Drew and Nicole Stott.Now poised for launch at pad 39A, Discovery has been upright on its mobile launcher platform a near-record 168 days. Only Columbia's 183-day stand on its platform before a 1990 astronomy mission was longer.